Fixtures having a cylindrical main body and a conically flaring upper portion or neck have been known and used in the art of dental implants for a long period of time. These fixtures are to be inserted into bore-holes in the jaw-bone in order to become osseointegrated to the bone tissue. The cylindrical parts generally osseointegrate correctly provided the proper techniques are used.
There are however some difficulties regarding the osseointegration around the conical neck portion of the implants which portion normally is smooth or polished. For some reason the bone tissue may degenerate around a smooth or polished conical part (bone resorbtion), leaving a pocket in the bone tissue around the conical part. The mechanism behind this is not quite clear. These pockets normally are accepted as inevitable although it is not entirely satisfactory that the implant is not entirely osseointegrated particularly since this pocket is formed in the strongest part of the bone tissue, the cortical bone.